Effect of laser welding and laser wire filling on forming and properties of dissimilar steel welded joints

In order to study the effects of different welding methods and different butt gaps on the microstructure and properties of welded joints of steel with unequal thickness, the medium carbon steel of 2 mm 50CrV and low carbon steel of 6 mm SPHE were used as test materials, and the welding was carried out by single laser and laser wire filling welding. The results show that the laser wire filling welding can reduce the welding cracks, and with the increase of the butt gap, the melt height gradually decreases, and the weld morphology transitions from Y shape to H shape. With the increase of the butt gap, the weld defects form. The hardness of weld center decreases with the increase of butt gap. The average hardness of weld formed by laser welding alone is the highest, and the highest hardness of welded joint is located in the heat affected zone of 50CrV medium carbon steel. The tensile strength of welded joints first increases and then decreases with the increase of butt gaps. When the butt gap is 0.6 mm, the surface morphology is good and the tensile strength is the highest. The fracture position of the welding test is on the side of the 2 mm 50CrV medium carbon steel.